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Re: Dog Urine vs. Concrete Wall

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How do you keep the same mechanism from damaging the earth anchors?

Daryl Richardson wrote:

> Fellow engineers,
>
>         Nineteen years ago I designed an L shaped cantilever retaining
> wall along the back alley of a residential property.  The high side of
> the earth backfill is on top of the footing, about five feet higher than
> the low side, and on the residence side of the wall.  Sulphate test at
> the time indicated that Type 1 portland cement was satisfactory for this
> use.  Granular backfill with proper drains was used behind the retaining
> wall; but the native soil in the area is silty clay.  General surface
> drainage is from the residence toward the retaining wall (at a very
> gentle slope).  Average annual precipitation in Calgary is about 17" per
> year.
>
>         A portion of the wall about 20" long is now leaning out (5" of
> movement observed).  The concrete generally appears to be in very good
> condition.  My interpretation of this movement is that the dowels
> connecting the footing to the wall may have rusted through.
>
>         Subsequent investigation reveals that the same family has owned
> the property for the entire nineteen years and that they have always
> owned two large dogs.  Furthermore, the dogs use the area immediately
> behind the retaining wall as their bathroom.  The ground surface for the
> first 8 to 10 feet from the retaining wall is washed smooth gravel (for
> the dogs) with the remainder of the 30 feet (more or less) to the house
> being ordinary lawn grass.  Lawn watering is generally required in
> Calgary with the general recommendations being not more than watering
> plus rain to total 1" per week.  Any excess would probably be absorbed
> into the ground in the area used by the dogs.
>
>         My expected solution to the problem is to install three drilled
> soil anchors through the retaining wall and into the undisturbed native
> soil behind the backfill and connected to a hollow structural on the
> face of the wall with epoxy coated or galvanized ties (possibly with an
> extra thickness for corrosion allowance).
>
>         Does anyone have any other ideas or information?  Am I way off
> base with my dog urine speculation?  I have never encountered this
> problem before.
>
>         Thank you for any help you may be able to give.
>
> Regards,
>
> H. Daryl Richardson
>
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